Chess Accuracy Calculator
How accuracy scores are calculated, why sites disagree, and the accuracy of your own game.
Winning chances 54.6% → 39.1% · move accuracy 50.5%
How chess accuracy is calculated
- Evaluation to winning chances. Each engine evaluation (in centipawns, capped at ±10 pawns) becomes a winning chance: Win% = 50 + 50 × (2 / (1 + e−0.00368208 × cp) − 1). Level positions are 50%; +3 pawns is about 75%.
- Move accuracy. For each move, compare your winning chances before and after it: Accuracy = 103.1668 × e−0.04354 × (Win% before − Win% after) − 3.1669 (+1 for imperfect analysis), between 0 and 100. A move that keeps your chances scores 100.
- Game accuracy. The move scores are combined twice: a mean weighted by how sharp the position was (the volatility of winning chances around the move), and a harmonic mean that punishes big blunders. The final score is the average of the two.
This is the formula Lichess publishes, and the one our free chess game review uses with Stockfish 19 at depth 12.
Why sites give different accuracy scores
| Site | Method | Published? |
|---|---|---|
| Lichess | Winning-chance formula above, Stockfish in the cloud or browser | Yes, open source |
| Chess.com | CAPS model on its own engine analysis | Description only |
| ChessAnalysis | Lichess formula, Stockfish 19 lite at depth 12 in your browser | Yes, on this page |
Check the accuracy of your own game
Frequently asked questions
What is a good chess accuracy?
It depends on the opponent and the time control. Club players often score 70–85% in blitz; 90%+ in a long game is excellent. Accuracy says how few chances you gave away, not how hard the position was, so a quiet game can score higher than a brilliant tactical one.
Why is my accuracy different on Chess.com and Lichess?
Chess.com uses its own model (CAPS) with its own engine settings; Lichess publishes a formula based on winning chances. Different engines, depths and formulas give different numbers for the same game. Compare your accuracy over many games on one site, not one game across sites.
Can I get 100% accuracy?
Yes, if every move keeps your winning chances at least where they were. Short games with a well-known opening often score very high; that says more about the length of the game than the strength of the play.